Sausage casings based on cellulose hydrate have been widespread for decades. The adhesion to scalded sausage meat emulsion is so great that the casing can only be taken off with tearing of the emulsion surface. In the case of dry or semi-dry sausage, the adhesion, in contrast, is so low that the casing, during sausage ripening, detaches (is cast off), does not co-shrink and forms pleats. In the intermediate space between casing and emulsion surface, frequently unwanted mold forms.
In order to improve, in the instance of dry or semi-dry sausage, the adhesion of the casing, various adhesion impregnations have been proposed which are applied to the inside of the casing. They contain, for example, cellulose-linked natural proteins, polyamide-polyamine-epichloro-hydrin resins, or chitosan which is covalently bonded to the cellulose using glyoxal.
For sausage casings having a smooth inner surface, as may be found in double-viscose-treated fibrous skins or in the case of cellophane skins, reactive adhesion components combined with an oil have proved advantageous. The oil component is, in particular, a triglyceride, paraffin oil or a silicone oil (DE 32 08 283). In addition, for dry or semi-dry sausage, internal impregnations have been developed which contain a combination of reactive release and adhesion components (DE 44 07 288). Using such an internal impregnation, a balanced relationship of good peelability with simultaneously sufficient adhesion may be achieved.
In addition, numerous release preparations have been developed. These contain, in particular, chromium-fatty acid complexes (U.S. Pat. No. 2,901,358), dialkylketenes having long-chain alkyl radicals (DE 14 92 699), perfluorinated compounds (DE 22 59 671) or lecithin (EP 0 502 431=U.S. Pat. No. 5,358,784).
As a result of industrial processing, increasingly high and more specific requirements are being made of the quality of sausage casings. For the pizza salami demanded in high amounts in the North American market, cellulose fiber skins are required which have an exact caliber constancy (that is there are virtually no variations in the diameter of the casing) and have a sufficiently rough surface so that long sections (up to about 3.2 m) can be pushed onto the stuffing horn without any problems. After a ripening time of only 10 to 12 days, the casing must be able to be peeled off very readily. For this the adhesion must be only very low. However, it must be sufficient so that the casing is not cast off, as a result of which space is formed in which mold can develop.
Particularly high requirements are made of a casing for mold-ripened California-type salami. This type of salami is ripened over a long period under optimum external conditions. If these conditions are not met, then the mold forms cellulases which break down the casing material. The casing must therefore be particularly easily peelable, so that even a casing attacked by cellulitic enzymes can still be taken off without defects. This task cannot be met using the internal impregnations known hitherto.
EP-A 676 143 (=U.S. Pat. No. 5,595,796) discloses a cellulose casing which is impregnated on the inside with a mixture of a release component and an adhesion component. The adhesion component is preferably a natural protein, chitosan, an aminoplast precondensate or a polyamine-polyamide-epichlorohydrin resin, whereas the release component is preferably a chromium-fatty acid complex or a diketene having long-chain fat-like substituents. This casing also cannot meet the requirements, since the adhesion-increasing action of the protein component is not sufficiently compensated for and covered by the adhesion-decreasing action of the dialkylketenes. The inside of the casing alone with chromium-fatty acid complexes (U.S. Pat. No. 2,901,358) or alone with dialkylketenes (DE 14 92 699) then leads itself to a detaching of the casing from the emulsion if this is only applied in a small amount. This route to a solution is thus likewise excluded.